The thermohaline circulation of the Arctic Ocean and the Greenland Sea

2019 ◽  
pp. 87-99
Author(s):  
Bert Rudels
Keyword(s):  
Arctic Ocean ◽  
Thermohaline Circulation ◽  
The Arctic ◽  
Greenland Sea ◽  
The Arctic Ocean

The thermohaline circulation of the Arctic Ocean and the Greenland Sea

1995 ◽  
Vol 352 (1699) ◽  
pp. 287-299 ◽  
Keyword(s):  
Surface Layer ◽  
Arctic Ocean ◽  
Thermohaline Circulation ◽  
Atlantic Water ◽  
The Arctic ◽  
Greenland Sea ◽  
Deep Circulation ◽  
Low Salinity ◽  
The North ◽  
The Arctic Ocean

The thermohaline circulation of the Arctic Ocean and the Greenland Sea is conditioned by the harsh, high latitude climate and by bathymetry. Warm Atlantic water loses its heat and also becomes less saline by added river run-off. In the Arctic Ocean, this leads to rapid cooling of the surface water and to ice formation. Brine, released by freezing, increases the density of the surface layer, but the ice cover also insulates the ocean and reduces heat loss. This limits density increase, and in the central Arctic Ocean a low salinity surface layer and a permanent ice cover are maintained. Only over the shallow shelves, where the entire water column is cooled to freezing, can dense water form and accumulate to eventually sink down the continental slope into the deep ocean. The part of the Atlantic water which enters the Arctic Ocean is thus separated into a low density surface layer and a denser, deep circulation. These two loops exit through Fram Strait. The waters are partly rehomogenized in the Greenland Sea. The main current is confined to the Greenland continental slope, but polar surface water and ice are injected into the central gyre and create a low density lid, allowing for ice formation in winter. This leads to a density increase sufficient to trigger convection, upwelling and subsequent ice melt. The convection maintains the weak stratification of the gyre and also reinforces the deep circulation loop. As the transformed waters return to the North Atlantic the low-salinity, upper water of the East Greenland Current enters the Labrador Sea and influences the formation of Labrador Sea deep water. The dense loop passes through Denmark Strait and the Faroe-Shetland Channel and sinks to contribute to the North Atlantic deep water. Changes in the forcing conditions might alter the relative strength of the two loops. This could affect the oceanic thermohaline circulation on a global scale

scholarly journals Deep-Water Flow over the Lomonosov Ridge in the Arctic Ocean

2005 ◽  
Vol 35 (8) ◽  
pp. 1489-1493 ◽  
Author(s):  
M-L. Timmermans ◽  
P. Winsor ◽  
J. A. Whitehead
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
Thermohaline Circulation ◽  
Global Climate ◽  
Volume Flow Rate ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Geothermal Heat ◽  
The Arctic Ocean ◽  
Canadian Basin

Abstract The Arctic Ocean likely impacts global climate through its effect on the rate of deep-water formation and the subsequent influence on global thermohaline circulation. Here, the renewal of the deep waters in the isolated Canadian Basin is quanitified. Using hydraulic theory and hydrographic observations, the authors calculate the magnitude of this renewal where circumstances have thus far prevented direct measurements. A volume flow rate of Q = 0.25 ± 0.15 Sv (Sv ≡ 106 m3 s−1) from the Eurasian Basin to the Canadian Basin via a deep gap in the dividing Lomonosov Ridge is estimated. Deep-water renewal time estimates based on this flow are consistent with 14C isolation ages. The flow is sufficiently large that it has a greater impact on the Canadian Basin deep water than either the geothermal heat flux or diffusive fluxes at the deep-water boundaries.

scholarly journals The Arctic Ocean as a dead end for floating plastics in the North Atlantic branch of the Thermohaline Circulation

2017 ◽  
Vol 3 (4) ◽  
pp. e1600582 ◽  
Author(s):  
Andrés Cózar ◽  
Elisa Martí ◽  
Carlos M. Duarte ◽  
Juan García-de-Lomas ◽  
Erik van Sebille ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
North Atlantic ◽  
Thermohaline Circulation ◽  
The Arctic ◽  
The North ◽  
Dead End ◽  
The Arctic Ocean ◽  
The North Atlantic

scholarly journals Arctic Ocean Freshwater Changes over the Past 100 Years and Their Causes

2008 ◽  
Vol 21 (2) ◽  
pp. 364-384 ◽  
Author(s):  
I. V. Polyakov ◽  
V. A. Alexeev ◽  
G. I. Belchansky ◽  
I. A. Dmitrenko ◽  
V. V. Ivanov ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Observational Data ◽  
Thermohaline Circulation ◽  
Atmospheric Precipitation ◽  
The Arctic ◽  
Central Basin ◽  
Central Arctic Ocean ◽  
The Arctic Ocean ◽  
Long Term Variations

Abstract Recent observations show dramatic changes of the Arctic atmosphere–ice–ocean system. Here the authors demonstrate, through the analysis of a vast collection of previously unsynthesized observational data, that over the twentieth century the central Arctic Ocean became increasingly saltier with a rate of freshwater loss of 239 ± 270 km3 decade−1. In contrast, long-term (1920–2003) freshwater content (FWC) trends over the Siberian shelf show a general freshening tendency with a rate of 29 ± 50 km3 decade−1. These FWC trends are modulated by strong multidecadal variability with sustained and widespread patterns. Associated with this variability, the FWC record shows two periods in the 1920s–30s and in recent decades when the central Arctic Ocean was saltier, and two periods in the earlier century and in the 1940s–70s when it was fresher. The current analysis of potential causes for the recent central Arctic Ocean salinification suggests that the FWC anomalies generated on Arctic shelves (including anomalies resulting from river discharge inputs) and those caused by net atmospheric precipitation were too small to trigger long-term FWC variations in the central Arctic Ocean; to the contrary, they tend to moderate the observed long-term central-basin FWC changes. Variability of the intermediate Atlantic Water did not have apparent impact on changes of the upper–Arctic Ocean water masses. The authors’ estimates suggest that ice production and sustained draining of freshwater from the Arctic Ocean in response to winds are the key contributors to the salinification of the upper Arctic Ocean over recent decades. Strength of the export of Arctic ice and water controls the supply of Arctic freshwater to subpolar basins while the intensity of the Arctic Ocean FWC anomalies is of less importance. Observational data demonstrate striking coherent long-term variations of the key Arctic climate parameters and strong coupling of long-term changes in the Arctic–North Atlantic climate system. Finally, since the high-latitude freshwater plays a crucial role in establishing and regulating global thermohaline circulation, the long-term variations of the freshwater content discussed here should be considered when assessing climate change and variability.

scholarly journals Recent Trends in Freshwater Influx to the Arctic Ocean from Four Major Arctic-Draining Rivers

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1189 ◽  
Author(s):  
Roxanne Ahmed ◽  
Terry Prowse ◽  
Yonas Dibike ◽  
Barrie Bonsal ◽  
Hayley O’Neil
Keyword(s):  
Arctic Ocean ◽  
Thermohaline Circulation ◽  
Global Climate ◽  
Ocean Dynamics ◽  
The Arctic ◽  
Freshwater Input ◽  
Discharge Data ◽  
The Arctic Ocean ◽  
Spring Freshet ◽  
Daily Discharge

Runoff from Arctic rivers constitutes a major freshwater influx to the Arctic Ocean. In these nival-dominated river systems, the majority of annual discharge is released during the spring snowmelt period. The circulation regime of the salinity-stratified Arctic Ocean is connected to global earth–ocean dynamics through thermohaline circulation; hence, variability in freshwater input from the Arctic flowing rivers has important implications for the global climate system. Daily discharge data from each of the four largest Arctic-draining river watersheds (Mackenzie, Ob, Lena and Yenisei; herein referred to as MOLY) are analyzed to identify historic changes in the magnitude and timing of freshwater input to the Arctic Ocean with emphasis on the spring freshet. Results show that the total freshwater influx to the Arctic Ocean increased by 89 km3/decade, amounting to a 14% increase during the 30-year period from 1980 to 2009. A distinct shift towards earlier melt timing is also indicated by proportional increases in fall, winter and spring discharges (by 2.5%, 1.3% and 2.5% respectively) followed by a decrease (by 5.8%) in summer discharge as a percentage of the mean annual flow. This seasonal increase in discharge and earlier pulse onset dates indicates a general shift towards a flatter, broad-based hydrograph with earlier peak discharges. The study also reveals that the increasing trend in freshwater discharge to the Arctic Ocean is not solely due to increased spring freshet discharge, but is a combination of increases in all seasons except that of the summer.

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